Methods for controlling the texture of alloys utilizing equal channel angular extrusion

ABSTRACT

Described is a high quality sputtering target and method of manufacture which involves application of equal channel angular extrusion.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is related to Application No. 09/098,761, filedJun. 17, 1998.

BACKGROUND OF THE INVENTION

[0002] The invention relates to sputtering targets and methods of makingsame; and to sputtering targets of high purity metals and alloys. Amongthese metals are Al, Ti, Cu, Ta, Ni, Mo, Au, Ag, Pt and alloys thereof,including alloys with these and or other elements. Sputtering targetsmay be used in electronics and semiconductor industries for depositionof thin films. To provide high resolution of thin films, uniform andstep coverages, effective sputtering rate and other requirements,targets should have homogenous composition, fine and uniform structure,controllable texture and be free from precipitates, particles and otherinclusions. Also, they should have high strength and simple recycling.Therefore, significant improvements are desired in the metallurgy oftargets especially of large size targets.

[0003] A special deformation technique known as equal channel angularextrusion (ECAE) described in U.S. Pat. Nos. 5,400,633; 5,513,512;5,600,989; and U.S. Pat. No. 5,590,389 is used with advantage inaccordance with the invention. The disclosures of the aforementionedpatents are expressly incorporated herein by reference.

SUMMARY OF THE INVENTION

[0004] The invention relates to a sputtering target made by a processincluding casting. The target has a target surface such that the surfaceof the target subjected to sputtering (referred to as target surface)has a substantially homogeneous composition at any location, substantialabsence of pores, voids, inclusions and other casting defects, grainsize less than about 1 μm and substantially uniform structure andtexture at any location. Preferably, the target comprises at least oneof Al, Ti, Cu, Ta, Ni, Mo, Au, Ag, Pt and alloys thereof.

[0005] The invention also relates to a method of manufacturing a target,as described above. The method comprises fabricating an article suitablefor use as a sputtering target comprising the steps of:

[0006] a. providing a cast ingot;

[0007] b. homogenizing said ingot at time and temperature sufficient forredistribution of macrosegregations and microsegregations; and

[0008] c. subjecting said ingot to equal channel angular extrusion torefine grains therein.

[0009] More particularly, a method of making a sputtering targetcomprising the steps of:

[0010] a. providing a cast ingot with a length-to-diameter ratio up to2;

[0011] b. hot forging said ingot with reductions and to a thicknesssufficient for healing and full elimination of case defects;

[0012] c. subjecting said hot forged product to equal channel extrusion;and

[0013] d. manufacturing into a sputtering target.

[0014] Still more particularly, a method of fabricating an articlesuitable for use as a sputtering target comprising the steps of:

[0015] a. providing a cast ingot;

[0016] b. solutionizing heat treating said cast ingot at temperature andtime necessary to dissolve all precipitates and particle bearing phases;and

[0017] c. Equal channel angular extruding at temperature below agingtemperatures.

[0018] After fabricating as described to produce an article, it may bemanufactured into a sputtering target.

DESCRIPTION OF THE DRAWINGS

[0019] FIGS. 1A-1D are schematic diagrams showing processing steps ofbillet preparation for ECAE;

[0020]FIG. 2 is a graph showing the effect of annealing temperature onbillet strength after 4 and 6 passes of ECAE for Al 0.5 wt.% Cu alloy;

[0021]FIG. 3A is a schematic diagram disclosing an apparatus forgradient annealing of targets;

[0022]FIG. 3B is a schematic diagram showing temperature distributionthrough target cross-section C-C during gradient annealing;

[0023]FIG. 4 is an illustration of (200) pole figures for Al 0.5 wt.% Cualloys processed with 2, 4 and 8 passes of route D, (in FIG. 5)respectively;

[0024]FIG. 5 is a graph showing the effect of number of passes and routeon texture intensity after ECAE of Al with 0.5 wt.% Cu;

[0025]FIG. 6 is a graph showing the effects of annealing temperature forroute A after ECAE of Al with 0.5 wt.% Cu;

[0026]FIG. 7 is a graph showing the effects of annealing temperature ontexture intensity for route B after ECAE of Al with 0.5 wt.% Cu;

[0027]FIG. 8 is a graph showing the effects of annealing temperature ontexture intensity for route C after ECAE of Al with 0.5 wt.% Cu;

[0028]FIG. 9 is a graph showing the effects of annealing temperature ontexture intensity for route D after ECAE of Al with 0.5 wt.% Cu:

[0029]FIG. 10 is a pole figure illustrating the texture as a result ofthe process described; and

[0030]FIGS. 11, 11A and 11B are schematic diagrams of an apparatus forECAE of billets for targets.

DETAILED DESCRIPTION

[0031] The invention contemplates a sputtering target having thefollowing characteristics:

[0032] substantially homogenous material composition at any location;

[0033] substantial absence of pores, voids, inclusions and other castingdefects;

[0034] substantial absence of precipitates;

[0035] grain size less than about 1μm;

[0036] fine stable structure for sputtering applications;

[0037] substantially uniform structure and texture at any location;

[0038] high strength targets without a backing plate;

[0039] controllable textures from strong to middle, weak and close torandom;

[0040] controllable combination of grain size and texture;

[0041] large monolithic target size;

[0042] prolonged sputtering target life;

[0043] optimal gradient of structures through target thickness. Targetspossessing these characteristics are producible by the processesdescribed.

[0044] Because of high purity, cast ingot metallurgy is useful in mostcases for billet fabrication in target production. However, castingresults in a very course dendritic structure with strong non-uniformityin the distribution of constitutive elements and additions across theingot and large crystallites. Moreover, high temperature and long-timehomogenizing cannot be applied in current processing methods because ofthe further increase of grains. One embodiment of the invention solvesthis problem by using homogenizing time and temperature sufficient forredistribution of macrosegregations and microsegregations followed byequal channel angular extrusion (ECAE) with a sufficient number ofpasses, preferably from 4 to 6, for grain refinement.

[0045] Another embodiment eliminates other casting defects such asvoids, porosity, cavities and inclusions which cannot be optimallyremoved by homogenizing and employs a hot forging operation. Incurrently known methods hot forging has a restricted application becausereductions are limited and are typically used at low temperature workingfor grain refinement. Other processes do not solve that problem whenslab ingots of the same thickness as the billet for ECAE are used. Inthe present invention, the as-cast ingot has a large length-to-diameterratio, preferably up to 2. During hot forging, the ingot thicknesschanges to the thickness of the billet for ECAE. That provides largereductions which are sufficient for full healing and elimination of castdefects.

[0046] Still another embodiment of the invention is directed toprecipitate-and particle-free targets. With currently known methodsprecipitate-free material may be prepared by solutionizing at the lastprocessing step. However, in this case heating to solutionizingtemperatures produces very large grains. The present invention providesa method for fabricating precipitate-free and ultra-fine grainedtargets. According to this embodiment of the invention, solutionizing isperformed at a temperature and time necessary to dissolve allprecipitates and particle bearing phases and is followed by quenchingimmediately before ECAE. Subsequent ECAE and annealing are performed attemperatures below aging temperatures for corresponding materialconditions.

[0047] A further embodiment of the invention is a special sequence ofhomogenizing, forging and solutionizing operations. As-cast ingots areheated and soaked at the temperature and for the length of timenecessary for homogenizing, then cooled to the starting forgingtemperature, then forged to the final thickness at the final forgingtemperature (which is above the solutionizing temperature) and quenchedfrom this temperature. By this embodiment all processing steps areperformed with one heating. This embodiment also includes anothercombination of processing steps without homogenizing: forging at atemperature of about the solutionizing temperature and quenchingimmediately after forging.

[0048] It is also possible in accordance with the invention to conductaging after solutionizing at the temperature and for the length of timenecessary to produce fine precipitates with an average diameter of lessthan 0.5 μm. These precipitates will promote the development of fine anduniform grains during following steps of ECAE.

[0049] An additional embodiment of the invention is a billet for ECAEafter forging. An as-cast cylindrical ingot of diameter d_(o) and lengthh_(o) (FIG. 1A) is forged into a disk of diameter D and thickness H(FIG. 1B). The thickness H corresponds to the thickness of the billetfor ECAE. Then two segments are removed from two opposite sides of theforged billet such as by machining or sawing (FIG. 1C), to provide adimension A corresponding to a square billet for ECAE (FIG. 1D). ECAE isperformed in direction “C” shown on FIG. 1C. After the first pass thebillet has a near-square shape if the dimensions of the ECAE billet(A×A×H), the dimensions of the forged disk (D×H) and the dimensions ofthe cast ingot (d_(o)×h_(o))are related by the following formulae:

D=1.18A

d_(o) ²h_(o)=1.39A²H

[0050] The invention further contemplates the fabrication of targetswith fine and uniform grain structure. ECAE is performed at atemperature below the temperature of static recrystallization with thenumber of passes and processing route adjusted to provide dynamicrecrystallization during ECAE. Processing temperature and speed are,correspondingly, sufficiently high and sufficiently low to providemacro-and micro-uniform plastic flow.

[0051] A method for fabricating fine and stable grain structures forsputtering applications and to provide high strength targets is alsoprovided. The billet after ECAE with dynamically recrystallizedsub-micron structure is additionally annealed at the temperature whichis equal to the temperature of the target surface during steadysputtering. Therefore, the temperature of the target cannot exceed thissputtering temperature and for structure to remain stable during targetlife. That structure is the finest presently possible stable structureand provides the best target performance. It also provides a highstrength target. FIG. 2 shows the effect of the annealing temperature onthe ultimate tensile strength and yield stress of Al 0.5 wt.% Cu alloyafter ECAE at room temperature with 6 or 4 passes. In both casesas-processed material has high strength not attainable for that materialwith known methods. Yield stress is only slightly lower than ultimatetensile strength. The increase of the annealing temperature in a rangefrom 125° C. to 175° C. that, it is believed, corresponds to possiblevariations of sputtering temperature results in the gradual decrease ofstrength. However, even in the worst case with an annealing temperatureof 175° C. target strength and, especially, yield stress are much higherthan the strength of aluminum alloy AA6061 at T-O condition which is themost widely used for fabrication of backing plates (see FIG. 2). Thus,among other things, the invention provides the following significantadvantages:

[0052] High strength monolithic targets may be fabricated from mildmaterials like pure aluminum, copper, gold, platinum, nickel, titaniumand their alloys.

[0053] It is not necessary to use backing plates with additional andcomplicated operations such as diffusion bonding or soldering.

[0054] Fabrication of large targets is not a problem.

[0055] Targets may easily be recycled after their sputtering life ends.

[0056] It is also useful to employ gradient annealing of targets afterECAE. For that purpose a preliminary machined target is exposed to thesame thermal conditions as under sputtering conditions and kept at thoseconditions a sufficient time for annealing. FIG. 3 describes thatprocessing. The target 1 is fixed in a device 2 which simulatessputtering: a bottom surface A of the target is cooled by water while atop surface B is heated to the sputtering temperature. Heating isadvantageously developed at the thin surface layer by radiant energy q(left side of FIG. 3A) or inductor 3 (right side of FIG. 3A) In additionit is also possible to achieve gradient annealing of targets directly ina sputtering machine at the regular sputtering conditions beforestarting the production run. In all these cases distribution oftemperature through the target as shown in FIG. 3B through sections C-Cof FIG. 1 is non-uniform and annealing takes place only inside a verythin surface layer (δ). Following sputtering the same distribution ismaintained automatically. Thus, structural stability and high strengthof as-processed material are conserved for the main part of the target.

[0057] An additional embodiment comprises a two-step ECAE processing. Atthe first step ECAE is performed with a low number of passes, preferablyfrom 1 to 3, in different directions. Then, the preliminary processedbillet receives aging annealing at low enough temperatures but forsufficient time to produce very fine precipitates of average diameterless than about 0.1 μm. After intermediate annealing ECAE is repeatedwith the number of passes necessary to develop a dynamicallyrecrystallized structure with the desired fine and equiaxed grains.

[0058] It is also possible through use of the invention to controltexture. Depending on the starting texture and the nature of thematerials, various textures can be created. Four major parameters areimportant to obtain controlled textures:

[0059] Parameter 1: the number of repeated ECAE passes subjected to thesame work piece. This number determines the amount of plasticdeformation introduced at each pass. Varying the tool angle between thetwo channels of the ECAE equipment enables the amount of plasticstraining to be controlled and determined and therefore represents anadditional opportunity for producing specific textures. Practically, inmost cases, a tool angle of about 90° is used since an optimaldeformation (true shear strain ε=1.17) can be attained;

[0060] Parameter 2: the ECAE deformation route; that is defined by theway the work piece is introduced through the die at each pass. Dependingon the ECAE route only a selected small number of shear planes anddirections are acting at each pass during plastic straining.

[0061] Parameter 3: annealing treatment that comprises heating the workpiece under different conditions of time and temperature. Bothpost-deformation annealing at the end of the ECAE extrusion andintermediate annealing between selected ECAE passes are effective waysto create various textures. Annealing causes the activation of differentmetallurgical and physical mechanisms such as second-phase particlegrowth and coalescence, recovery and static recrystallization, which allaffect more or less markedly the microstructure and texture ofmaterials. Annealing can also create precipitates or at least change thenumber and size of those already present in the material: this is anadditional way to control textures.

[0062] Parameter 4: the original texture of the considered material.

[0063] Parameter 5: the number, size and overall distribution ofsecond-phase particles present inside the material.

[0064] With consideration of these five major parameters, control oftexture is possible in the ways described below:

[0065] Table 1 describes major components of texture between 1 and 8ECAE passes via routes A through D in the as deformed condition for astrong initial texture and also for routes A and D for a weak initialtexture. To describe major components both the 3 Euler angles (αβγ)according to the Roe/Matthies convention and ideal representation {xyz}<uvw> are used. Moreover, the total volume percentage of the componentis given. For texture strength both the OD index and Maximum of polefigures are given. TABLE 1 Texture strength and orientation for route Aas a function of the number of passes and initial texture Number MajorTexture Orientations Notation: OD Maximum of of Euler angles(αβγ):{xyz}<uvw>:% total index Pole Figures passes N volume with 5°spread (t.r.) (t.r.) ROUTE A (STRONG INITIAL TEXTURE) Original (10.954.7 45):(−111)<1-23>:16% 21.7 17.02 (N = 0) (105 26.50):(−102)<-28-1>:14% (110 24 26.5):(−215)<-5-5-1>:9.3% N = 1 (119 26.50):(−102)<-2-4-1>:17.62% 10.9 10.9 (346 43.3 45):(−223)<2-12>:7.62% N =2 (138 26.5 0):(−102)<-2-2-1>:8.66% 6.1 6.9 (31 36.726.5):(−213)<-3-64>:8.6% N = 3 (126.7 26.5 0):(−102)<-2-3-1>:7.45% 5.795.45 (21 36.7 26.5):(−213)<2-43>:6.1% N = 4 (26.5 36.726.5):(−213)<2-64>:9.42% 4.82 6.55 (138 26.5 0):(−102)<-2-2-1>:4.62% 16915.8 45):(−115)<-32-1>:4.32% N = 6 (126.7 26.5 0):(−102)<-2-3-1>:6.66%3.94 5.61 (228 33.7 0):(−203)<-34-2>:5.8% (31 36.726.5):(−213)<3-64>:3.42% N = 9 (0 35.2 45):(−112)<1-11>:3.1% 2.05 3.5(180 19.4 45):(−114)<-22-1>:3.06% (31 25.2 45):(−113)<1-52>:2.2% ROUTE A(WEAK INITIAL TEXTURE) Original (80 25.2 45):(−113)<8-11 1>:4.3% 2.6 3.2(N = 0) Large spreading around (106) (119) N = 1 (0 46.745):(−334)<2-23>:5.8% 4.02 6.3 (222 26.5 0):(−102)<-22-1>:5% (128 18.40):(−103)<-3-4-1>:4.01% N = 2 (126.7 26.5 0):(−102)<-2-3-1>:6.22% 4.46.8 (26.5 48.2 26.5):(−212)<1-22>:5.4% (162 13.2 45):(−116)<-42-1>:5.4%N = 4 (226 36.7 26.5):(−213)<-12-1>:4.85% 3 5.1 (233 26.50):(−102)<-23-1>:4.63% (136 19.5 45):(−114)<-40-1>:4.54% (26.5 36.726.5):(−213)<2-64>:3.7% ROUTE B (STRONG INITIAL TEXTURE) Original (10.954.7 45):(−111)<1-23>:16.4% 21.7 17.02 (N = 0) (105 26.50):(−102)<-2-8-1>:14% (110 24 26.5):(−215)<-5-5-1>:9.3% N = 1 (119 26.50):(−102)<-2-4-1>:17.62% 10.9 10.9 (346 43 45):(−223)<2-12>:7.62% N = 2(0 48 26.5):(−212)<425>P24.24% 17.27 14.02 (216 15.845):(−115)<-24-1>:8.07% (138 26.5 0):(−102)<-2-2-1>:5.04% N = 3 (260 3674):(−2 7 10)<94-1>:15.49% 7.3 9.1 (118 18.4 90):(013)<-63-1>:5.23% N =4 (96 36 16):(-7 2 10)<-6-15-1>:12% 6 9.77 (187 15.626.5):(-21-8)<-32-1>:8.05% N = 6 (230.5 14 0):(−104)<-45-1>:12.46% 6.38.45 (100 36 16):(-7 2 10)<-4-9-1>:10.2% N = 8 (230.5 140):(−104)<-45-1>:9.19% 4.9 6.99 (180 13.2 45):(−116)<-33-1>:8.21% (10036 16):(-7 2 10)<-4-9-1>:7.48% ROUTE C (STRONG INITIAL TEXTURE) Original(10.9 54.7 45):(−111)<1-23>:16.4% 21.7 17.02 (N = 0) (105 26.50):(−102)<-2-8-1>:14% (110 24 26.5):(−215)<-5-5-1>:9.3% N = 1 (119 26.50):(−102)<-2-4-1>:17.62% 10.9 10.9 (346 43 45):(−223)<2-12>:7.62% N = 2(0 34.5 14):(−416)<4-13>:43.3% 48.9 25.9 (221.8 265 0):(−102)<-2 2-1>:10.5% N = 3 (254 148.4 0):(−103)<-3 11 -1>:7.5% 5.2 6.05 (111.5 46.518.4):(−313)<-2-3-1>: 6.6% N = 4 (130 36.9 10):(−304)<-4-6-3>:15.05%7.95 13.3 N = 5 Large spreading 2.4 3.3 (270 14 0):(−104)<010>:4.66%(26.5 48 26.5):(−212)<1-22>:2.54% N = 6 (110 36 16):(-7 210)<-5-8-2>:11.6% 6.32 9.3 (234 33.7 0):(−203)<-35-2>:5.7% N = 7 Largespreading 2.35 3.15 (242 18.4 0):(−103)<-36-1>:4.66% (188 11.445):(−117)<-34-1>:3.36% N = 8 (136.5 18.4 0):(−103)<-331>:14.71% 12.9 11(257 45 0):(−101)<-8 49 -8>:8.75% ROUTE D (STRONG INITIAL TEXTURE)Original (10.9 54.7 45):(−111)<1-23>:16.4% 21.7 17.02 (N = 0) (105 26.50):(−102)<-2-8-1>:14% (110 24 26.5):(−215)<-5-5-1>:9.3% N = 1 (119 26.50):(−102)<-2-4-1>:17.62% 10.9 10.9 (346 43 45):(−223)<2-12>:7.62% N = 2(0 48 26.5):(−212)<425>:24.24% 17.27 14.02 (216 15.8 45):(−115)<-2 4-1>:8.07% (138 26.5 0):(−102)<-2-2-1>:5.04% N = 3 (197 20.426.5):(−216)<-22-1>:9.57% 3.91 6.67 all other components < 3% N = 4 (22226.5 0):(−102)<-22-1>:13.34% 6.346 7.36 all other components < 3.8% N =6 (223.5 18.5 0):(−103)<-33-1>:7.4% 2.72 4.26 all other components <2.5% N = 8 (222 26.5 0):(−102)<-22-1>:3.42% 1.9 3.01 all othercomponents < 3% ROUTE D (WEAK INITIAL TEXTURE) Original (80 25.245):(−113)<-8 -11 1>:4.3% 2.6 3.2 (N = 0) Large spreading around (106)(119) N = 1 (0 46.7 45):(−334)<2-23>:5.8% 4.02 6.3 (221 26.50):(−102)<-22-1>:5% (128 18.4 0):(−103)<-3-4-1>:4.01% N = 2 (241 26.50):(−102)<-24-1>:12.72% 5 6.7 (26.5 48.2 26.5):(−212)<1-22>:4.1% N = 3(197 20.˜ 26.5):(-216)<-22-1>:8.8% 3.5 6.44 (26.5 48.226.5):(−212)<1-22>:3.9% N = 4 (221.8 26.5 0):(−102)<-22-1>:7.2% 3 5.3(26.5 48.2 26.5):(−212)<1-22>:3.1%

[0066] Table 2 describes major components of features between 1 and 8ECAE passes via route A through D for a strong initial texture and afterannealing at (150C, 1h), (225C, 1h) and (300C, 1h) TABLE 2 Major textureorientations for route A in function of number of passes N and annealingtemperature Notations: Euler angles (αβγ):{xyz}<uvw>:% total volume with5° spread N Annealing at (150 C., 1h) Annealing at (225 C., 1h)Annealing at (300 C., 1h) ROUTE A (STRONG INITIAL TEXTURE) 1 (43 4722):(−525)<1-32>: (35 48 25):(−212)<1- (76 29.5 45):(−225)<- 10.4%22>:13.15% 5-71>:9.3% (110 26.5 0):(−102)<-2-6- (114 22 10):(−102)<-(141 37 0):(−304)<-4- 1>:8.04% 2-4-1>:9.3% 4-3>:6.6% (130 2418.4):(−317)<-3- 2-1>:7.15% 2 (105 22 0):(−205)<-5 20- (136 18.40):(−103)<- (354 18.4 0):(- 2>: 9.21% 3-3-1>:20.9% 103)<913>:7.74% (15519.5 45):(−114)<-31- (112 19 18.4):(− (315 11.5 45):(- 1>:7.83%319)<-5-6-1>:20.2% 117)<701>:7.38% (31 36.7 45):(−213)<3- (90 70):(−108)<0-10>: 64>:6.88% 6.7% 3 (110 36 16):(-7 2 10)<-4- (110 450):(−101)<-1- Large spreading around 9-2>:15.2% 4-1>:16.85% (117), (100)(233 26.5 0):(−102)<-23- (290 45 0):(− All components < 4% 1>:7.35%101)<141>:11.5% 4 (129 18 26):(−217)<-1-5- (124 25 14):(−419)<- (11025.2 45):(−113)<- 1>:11.73% 3-3-1>:12.4% 6-3-1>:6.87% (35 3726.5):(−213)<-2- (38 36.7 26.5):(− (318 25.2 45):(− 53>:11.2%213)<3-95>:7.5% 113)<301>:5.1% 6 (180 19.5 45):(−114)<-22- Largespreading (46.7 19.5 45):(− 1>:5.5% All components < 5% 114)<-1-17 4>:9%(135 10 0):(−106)<-6-6- All components < 4.9% 1>:4% (0 46.745):(−334)<2-23>: 3.95% 8 Large spreading around (44 36 26.5):(− (152 320):(−508)<-8- (315), 213)<2-63>:7.94% 5-5>:6.4% (104) (136 18.40):(−103)<- All components < 3% All components < 4% 3-3-1>:6.17% ROUTE B(STRONG INITIAL TEXTURE) 1 (43 47 22):(−525)<1-32>: (35 4825):(−212)<1-22>: (76 29.545):(−225)<- 10.4% 13.15% 5-71>:9.3% (110 26.50):(−102)<-2-6- (114 22 10):(−102)<-2-4- (141 37 0):(−304)<-4- 1>:8.04%1>:9.3% 4-3>:6.6% (130 24 18.4):(−317)<-3- 2-1>:7.15% 2 (215 2026.5):(−216)<-36 (112 34 0):(−203)<-3-9- (221 26.5 0):(−102)<- 2>:35%2>:16% 22-1>:13.3% (270 13.2 45):(− (16 54.7 45):(−111)<1- (109 140):(−104)<-4- 116)<110>: 34>:8.88% 12-1>:12% 16% 3 (148 19 79):(-1 515)<- (10 45 10):(−616)<3- (0 48 26.5):(−212)<4- 55-2>:17.5% 13>:5.7%25>:6% (90 16 45):(−115)<-1- (235 14 0):(−104)<46- (222 41 45):(- 10>:1>:4.53% 223)<03-2>:5.8% 6.9% Large spreading (19.5 45 0):(−101)<2-12>:5.4% 4 (127 26.5 0):(−102)<-2-3- (230 14 0):(−104)<-45- Largespreading 1>:5.9% 1>:6.23% around (107) (115) (242 14 0):(−104)<-4 8-All components < 3% 1>:6 6 (180 19.5 45):(−114)<-22- Large spreading(46.7 19.5 45):(- 1>:5.5% All components < 5% 114)<-1-17 4>:9% (135 100):(−106)<-6-6- All components < 4.9% 1>:4 (0 46.7 45):(−334)<2-23>:3.95% 8 Large spreading around (44 36 26.5):(−213)<2- (153 320):(−508)<-8- (315), (104) 63>:7.94% 5-5>:6.4% All components < 4% (13618.4 0):(−103)<-3- All components < 3% 3-1>:6.17% ROUTE C (STRONGINITIAL TEXTURE) 1 (43 47 22):(−525)<1-32>: (35 48 25):(−212)<1- (7629.5 45):(−225)<-5- 10.4% 22>:13.15% 71>:9.3% (110 26.5 0):(−102)<-2-(114 22 10):(−102)<-2- (141 37 0):(−304)<-4-4- 6-1>:8.04% 4-1>:9.3%3>:6.6% (130 24 18.4):(−317)<-3- 2-1>:7.15% 2 (191 16 45):(−115)<-23-(99 46 14):(−414)<-3-8- Large spreading around 1>:8.77% 1>:20.9% (100)(156 26.5 0):(−102)<-2- (289 45 0):(−101)<141>: All components < 3.8%1-1>:6.68% 15.22% 3 (119 26.50):(−102)<-2- (106 29 26.5):(−214)<- (19414 0):(−104)<-41- 4-1>:28.4% 5-6-1>:19.5% 1>:6.1% (26.5 4826.5):(−212)<1- (103 31 34):(−326)<-6- (163 18.4 0):(−103)<-3- 22>:9.74%6-1>:18.7% 1-1>:5.85% (42 46.5 18.4):(−313) <1-32>:8.83% 4 105 3818.5):(−314)<-3- Large spreading around Large spreading around5-1>:10.2% (302) and (225) (100) (105) (116) Other components < 5.3% Allcomponents < 2.8% All components < 4.1% 5 (103 32 18.4):(-3 1 5)<- (12726.5 0):(−102)<-2- Large spreading around 4-7-1>:19% 3-1>:7% (106) (115)(22 38 18.4):(−314)<1- All components < 3.7% 11>:5.6% 6 (61 4614):(−414)<1- Large spreading around (80 25 45):(−113)<-8-11 83>:11.82%(101) and (334) 1>:4.3% (155 21 18.4):(−318)<- All components < 4% Allcomponents < 3% 22-1>:7.94% 7 (104 36 16):(-7 2 10)<- (125 370):(−304)<-47- Large spreading around 3-6-1>:29% 3>:7.8% (100) (105)(203) (26.5 48 26.5):(−212)<1- (305 45 0):(−101)<121>: All components <2.9% 22>:7.6% 5.82% 8 (104 47 22):(−525)<-3-5- (106 38 18.4):(−314)<-Large spreading around 1>:15.36% 3-5-1>4.64% (100) (105) (112) (203) Allcomponents < 3.2% All components < 2.7% ROUTE D (STRONG INITIAL TEXTURE)1 (43 47 22):(−525)<1-32>: (35 48 25):(−212)<1-22>: (76 29.545):(−225)<- 10.4% 13.15% 5-71>:9.3% (110 26.5 0):(−102)<-2-6- (114 2210):(−102)<-2-4- (141 37 0):(−304)<-4- 1>:8.04% 1>:9.3% 4-3>:6.6% (13024 18.4):(−317)<-3- 2-1>:7.15% 2 (215 21 26.5):(−216)<-36 (112 340):(−203)<-3-9- (222 26.5 0):(−102)<- 2>:35% 2>:16.45% 22-1>:13.3% (27013 45):(−116)<110>: (16 54.7 45):(−111)<1- (109 14 0):(−104)<-4- 16%34>:8.88% 12-1>:12% (162 9 45):(−119)<- 63-1>:9.6% 3 (337 50 34):(− (16820 25):(−216)<-82- (150 16 45):(− 323)<101>:12.2% 3>:10.35%115)<115)<-41-1>: 5.6% (215 47 45):(−334)<0 4- (102 18.4 0):(−103)<-3-(198 18.4 0):(−103)<- 3>:9.75% 16-1>:9.32% 31-1>:5.2% (24126.50):(−102)<-24- (162 13 45):(−116)<-42- 1>:7.02% 1>:6.44% 4 (233 26.50):(−102)<-23- Large spreading Large spreading 1>:9% All components <3.6% around (105) (116) All other components < 4% All components < 3.9%6 (224 18.4 0):(−103)<-33- (224 18.4 0):(−103)<-33- Large spreading1>:8.29% 1>:5.49% around (106) and All other components < (109 18.40):(−103)<-3- (113) 3.8% 9-1>:4.4% All components < 2.9% 8 (222 270):(−102)<-22- (205 21 18.4):(−138)<- (222 26.5 0):(−102)<- 1>:8.58%22-1>:11.44% 22-1>:8.58% All components < 4% (233 26.5 0):(−102)<-23-(38 16 45):(−115)<1- 1>:10.74% 92>:5.55%

[0067] (1) The number of ECAE passes permits the control of texturestrength. The increase of the number of passes is an efficient mechanismof randomizing texture. There is an overall decrease of texture strengthevidenced by the creation of new orientations and, more importantly, thelarge spreading of orientations around the major components of thetexture as evidenced in FIG. 4. FIG. 4 is an illustration of (200) polefigures for Al with 0.5 wt.% Cu alloys processed 2, 4 and 8 passes ofroute D (FIG. 5) and shows spreading of orientations as “N” increases.This phenomenon is more or less effective depending on the investigatedroute and/or annealing treatment. For example in the as-deformed state,routes B and C result in somewhat higher textures than routes A and D(FIG. 5 and Table 1). FIG. 5 is a graph that shows the influence of ECAEdeformation route and strength on texture formation as a function ofnumber of ECAE passes. For medium to very strong starting textures, twomain areas can be distinguished in the as-deformed state (FIG.5):

[0068] Between passes 1 and 4 (with a tool angle of 90°), very strong tomedium textures are obtained. In the investigation of A1.5Cu, forexample, the OD index ranges from more than 7 times random to more than48 times random which corresponds to maximum intensities of the ODFbetween 3000 mrd (30 times random) and more than 20000 mrd (200 timesrandom).

[0069] For more than 4 passes (with a tool angle of 90°), medium-strongto very weak textures close to random are created. In the case of A1.5Cualloys, OD index varies from around 11 times random to less than 1.9times random depending on the route, which corresponds to maximumintensities of the ODF between 7000 mrd (70 times random) and around 800mrd (8 times random).

[0070] The two main domains are maintained after subsequent annealing,as shown in the graphs of FIGS. 6, 7, 8 and 9. However for some ECAEdeformation routes (for example route B and C in the case of A1.5Cu),additional heating can give a strong texture, as discussed below. Theexistence of these two areas is a direct consequence of themicrostructural changes occurring in the material during intensiveplastic deformation. Several types of defects (dislocations, microbands,shear bands and cells and sub-grains inside these shear bands) aregradually created during the 3 to 4 ECAE passes (for a tool angle of90°). The internal structure of materials is divided into differentshear bands while increasing the number of passes. After 3 to 4 ECAEpasses, a mechanism termed dynamic recrystallization occurs and promotesthe creation of sub-micron grains in the structure. As the number ofpasses increases these grains become more and more equiaxed and theirmutual local mis-orientations increase giving rise to a higher number ofhigh angle boundaries in the structure. The very weak and close torandom textures that are created are a consequence of three majorcharacteristics of the dynamically recrystallized microstructures: thepresence of high internal stresses at the grain boundaries, the largenumber of high angle boundaries and the very fine grain size with alarge grain boundary area (usually of the order of about 0.1-0.5 μm).

[0071] (2) The ECAE deformation route permits control of the majororientations of the texture. Depending on the route, different shearplanes and directions are involved at each pass (see FIG. 5 and Tables 1and 2). Therefore shear bands of different orientations are created inthe structure. For some routes these shear bands always intersect eachother in the same way; for other routes new families are constantlyintroduced at each pass (Tables 1 and 2). All these options allowchanges to the major components or orientations between each pass. Theeffect is particularly strong for a small number of passes before theadvent of dynamic recrystallization, as discussed above. An importantapplication exists in the possibility to create different types ofstrong textures already in the as-deformed state for a limited number ofECAE passes.

[0072] (3) Additional annealing has an important influence on both themajor texture orientations and strength (see FIGS. 6, 7, 8, 9 and Table2).

[0073] For annealing temperatures below the static recrystallization, achange in both texture strength and main orientation is observed. Thiseffect can be particularly strong for a low number of passes (less thanabout 4 passes) leading to remarkable migrations of major orientationsaccompanied with either a decrease or increase of texture strength. Suchchanges can be attributed to the instability of microstructural defectswhich are implemented in the crystal structure. Complex mechanisms suchas recovery and sub-grain coalescence explain partly the observedphenomena. For dynamically recrystallized ultra-fine structure (afterusually 4 passes) smaller modifications are encountered. They areusually associated with the transition from a highly stressed to a moreequilibrium micro structure.

[0074] For annealing temperatures close to the beginning of staticrecrystallization, the same over-all results as in the above case arefound. However, it is important to note that new and different texturesthan for low temperature annealing can be obtained, especially for a lownumber of ECAE passes (Table 2). This is due to static recrystallizationwhich creates new grains with new orientations by diffusion mechanisms.

[0075] For annealing temperatures corresponding to developed stages ofstatic recrystallization (full static recrystallization), textures tendto be weakened (as shown in FIGS. 6, 7, 8, 9 and Table 2). This isparticularly true after 3 or 4 ECAE passes where very weak and almostrandom textures are created. These textures are characterized by four,six or eight fold symmetry with a higher number of cube (<200>)components.

[0076] Additional textural analysis of ECAE deformed Al and 0.5 wt.% Cuis shown in the pole figure described in FIG. 10. In this case thesample was given an initial thermochemical treatment of casting plushomogeneous plus hot forging plus cold rolling (˜10%) plus two ECAEpasses via route C plus annealing (250° C., 1 hour). The recrystallizedmicrostructure had grain size of 40-60 μm and strong texture along{−111}<2−12>, {012}<−130>, {−133}<3−13>. The result shows two ECAEpasses (C) plus static recyrstalization permits removal of the verystrong (220) textural component of the as-forged condition.

[0077] By taking into account all the foregoing, results show thatintermediate annealing between each pass provides several additional andsignificant opportunities to adjust desired textures. Two options areavailable:

[0078] A. Intermediate annealing either at low temperature or just atthe beginning of static recrystallization after a low number of passes(N<4) can give strong textures with new orientations after subsequentdeformation with or without annealing.

[0079] B. Intermediate annealing in the case of full staticrecrystallization after a low or high number of passes can lead moreeasily to very weak textures after subsequent deformation with orwithout annealing.

[0080] It is also possible to repeat intermediate annealing severaltimes in order to enhance the effects described above.

[0081] (4) Starting texture has also a strong influence on both textureand strength especially after a limited number of passes (usually after1 to 4 passes). For a higher number of passes the ECAE deformation isvery large and new mechanisms are taking place which lessen themagnitude of the influence of the starting texture. Two situations arenoted (FIG. 5 and Table 1 for route A and D):

[0082] A. For a strong to medium starting textures, after furtherdeformation with or without annealing, it is possible to obtain verystrong to medium textures before 4 passes and strong-medium to very weaktextures after approximately 4 passes according to the results describedin paragraph 1, 2 and 3.

[0083] B. For medium to very weak starting textures it will be moredifficult to obtain very strong to strong textures at least in theas-deformed state. Weak starting textures are more likely to enhance andpromote weak to random textures after ECAE deformation with or withoutannealing (Table 1).

[0084] (5) Second phase particles have a pronounced effect on texture.Large (>1 μm) and non-uniformly distributed particles are not desiredbecause they generate many problems such as arcing during sputtering.Very fine (>1 μm) and uniformly distributed second phase particles areof particular interest and offer many advantages. Firstly, they tend tocreate a more even stress-strain state during ECAE deformation.Secondly, they stabilize the already ECAE-deformed microstructure inparticular after further annealing. In this case particles pin grainboundaries making them more difficult to change. These two major effectsevidently affect the texture of materials. Especially:

[0085] for a small number of passes (<4 passes), the effects describedpreviously in sections (1) to (4) can be enhanced due to the presence ofsecond phase particles in particular for strong textures.

[0086] for a large number of passes, second phase particles areeffective in promoting the randomization of texture.

[0087] In order to take advantage of the possibilities offered by theECAE technique in terms of texture control, three types of results canbe achieved:

[0088] A. Materials (sputtering targets) with strong to very strong(ODF>10000 mrd) textures. In particular this can be obtained for a smallnumber of passes with or without subsequent annealing or intermediateannealing. A strong starting texture is a factor favoring the creationof strong textures. For example in the case of A1.5Cu alloy Table 1gives all the major components of orientations which were created fordifferent deformation routes (A,B,C,D) between 1 and 4 passes. Theas-deformed state as well as deformation followed either by lowtemperature annealing (150° C., 1h) or by annealing at the beginning ofstatic recrystallization (225° C., 1h) or after full recrystallization(300° C., 1h) are considered in this table. The original texture isdisplayed in FIG. 7. It is important to note that in most cases newtypes of textures have been found. Not only {200} and {220} textures arepresent but also {111}, {140}, {120}, {130}, {123}, {133}, {252} or, forexample, {146}. For strong textures, one or two main components areusually present.

[0089] B. Material (sputtering targets) with weak to close to randomtextures with an ultra-fine grain size less than 1μm. Whatever the routethis can be obtained after more than 3 to 4 ECAE passes followed or notby annealing or intermediate annealing at a temperature below thebeginning of recrystallization temperature. A very weak starting textureis a factor favoring the creation of close to random textures.

[0090] C. Statically recrystallized materials (sputtering targets) withweak to close to random textures with a fine grain size aboveapproximately 1 μm. Whatever the route this can be obtained after morethan 3 to 4 ECAE passes followed by annealing or intermediate annealingat a temperature above the beginning of recrystallization temperature. Avery weak starting texture is a factor favoring the creation of close torandom textures.

[0091] Another embodiment of the invention is an apparatus forperforming the process to produce targets. The apparatus (FIGS. 11, 11Aand 11B) includes die assembly 1, die base 2, slider 3, punch assembly4,6 hydraulic cylinder 5, sensor 7, and guide pins 11. Also the die isprovided with heating elements 12. Die assembly 1 has a vertical channel8. A horizontal channel 9 is formed between die assembly 1 and slider 3.The die is fixed at table 10 of press, punch assembly 4, 6 is attachedto press ram. In the original position a-a the forward end of slider 3overlaps channel 1, punch 4 is in a top position, and a well lubricatedbillet is inserted into the vertical channel. During a working strokepunch 4 moves down, enters channel 8, touches the billet and extrudes itinto channel 9. Slider 3 moves together with billet. At the end ofstroke the punch reaches the top edge of channel 9 and then returns tothe original position. Cylinder 5 moves the slider to position b-b,releases the billet, returns the slider to the position a-a and ejectsthe processed billet from the die. The following features are noted:

[0092] (a) During extrusion slider 3 is moved by hydraulic cylinder 5with the same speed as extruded material inside channel 9. To controlspeed, the slider is provided with sensor 7. That results in fullelimination of friction and material sticking to the slider, in lowerpress load and effective ECAE;

[0093] (b) Die assembly 1 is attached to die base 2 by guide pins 11which provide free run δ. During extrusion the die assembly is nestledto the base plate 2 by friction acted inside channel 8. When the punchreturns to the original position, no force acts on the die assembly andslider, and cylinder 3 can easily move the slider to position b-b andthen eject the billet from the die.

[0094] (c) Three billet walls in the second channel are formed by theslider (FIG. 11A) that minimizes friction in the second channel.

[0095] (d) The side walls of the second channel in the slider areprovided with drafts from 5° to 12°. In this way the billet is keptinside the slider during extrusion but may be ejected from the sliderafter completing extrusion. Also, thin flash formed in clearancesbetween the slider and die assembly may be easily trimmed.

[0096] (e) Die assembly is provided with heater 12 and springs 13.Before processing, springs 13 guarantee the clearance δ between dieassembly 1 and die base 2. During heating this clearance providesthermoisolation between die assembly and die base that results in shortheating time, low heating power and high heating temperature.

[0097] The apparatus is relatively simple, reliable and may be used withordinary presses.

We claim:
 1. A sputtering target made by a process including castinghaving a target surface with the following characteristics: a)substantially homogenous composition at any location; b) substantialabsence of pores, voids, inclusions and other casting defects; c)substantial absence of precipitates; d) grain size less than about 1μm;and e) substantially uniform structure and texture at any location.
 2. Asputtering target according to claim 1 comprising Al, Ti, Cu, Ta, Ni,Mo, Au, Ag, Pt.
 3. A sputtering target according to claim 1 comprisingA1 and about 0.5 wt.% Cu.
 4. A method for fabricating an articlesuitable for use as a sputtering target comprising the steps of: a.providing a cast ingot; b. homogenizing said ingot at time andtemperature sufficient for redistribution of macrosegregations andmicrosegregations; and c. subjecting said ingot to equal channel angularextrusion to refine grains therein.
 5. A method according to claim 4further comprising, after subjecting said ingot to equal channel angularextrusion to refine grains therein, manufacturing same to produce asputtering target.
 6. A method according to claim 4 wherein said ingotis subject to 4 to 6 passes of equal channel angular extrusion.
 7. Amethod of making a sputtering target comprising the steps of: a.providing a cast ingot with a length-to-diameter ratio up to 2; b. hotforging said ingot with reductions and to a thickness sufficient forhealing and full elimination of case defects; c. subjecting said hotforged product to equal channel extrusion; and d. manufacturing into asputtering target.
 8. A method of fabricating an article suitable foruse as a sputtering target comprising the steps of: a. providing a castingot; b. solutionizing heat treating said cast ingot at temperature andtime necessary to dissolve all precipitates and particle bearing phases;and c. Equal channel angular extruding at temperature below agingtemperatures.
 9. A method according to claim 8 further comprisingmanufacturing to produce a sputtering target.
 10. A method according toclaim 4 including: a. homogenizing the ingot; b. hot forging of theingot; and c. Equal channel angular extruding forged billet.
 11. Amethod according to claim 7 including: a. hot forging the ingot; and b.equal channel angular extruding the forget billet.
 12. A methodaccording to claim 10 further comprising producing a sputtering target.13. A method according to claim 11 further comprising producing asputtering target.
 14. A method according to claim 1 further comprisinga solutionizing heat treatment prior to equal channel angular extrusion.15. A method according to claim 1 further comprising water quenchingafter homogenizing.
 16. A method according to claim 7 including: a.heating the cast ingot before forging at a temperature and for a timesufficient for solutionizing; b. hot forging at a temperature abovesolutionizing temperature; and c. water quenching the forged billetimmediately after forging.
 17. A method according to claim 4 including:a. cooling the ingot after homogenizing to a forging temperature abovethe solutionizing temperature; b. Hot forging at a temperature above thesolutionizing temperature; and c. water quenching the forged billetimmediately after forging step.
 18. A method according to claims 4, 7 or8 including aging after solutionizing and water quenching at atemperature and for a time sufficient to produce fine precipitates withan average diameter of less than 0.5 μm.
 19. A billet for equal channelangular extrusion of targets fabricated from a cast ingot of diameter doand length ho which has been forged into a disc of diameter d_(o) andthickness h_(o) and from which two segments from two opposite sides offorged billet to provide a billet width A have been removed in such amanner that thickness H corresponds to the thickness of the billet forequal channel angular extrusion, the wide A corresponds to the dimensionof square billet for equal channel angular extrusion, and dimensions ofthe cast ingot and the forged billet are related by the formulae:D=1.18A d_(o) ²h_(o)=1.39.A²H
 20. A method according to claims 4, 7 or 8in which the step of equal channel angular extrusion is performed at atemperature below the temperature of static recrystallization and at aspeed sufficient to provide uniform plastic flow, and for a number ofpasses and routes that provides dynamic recrystallization duringprocessing.
 21. A method according to claims 5, 9 or 13 includingannealing after final target fabrication at the temperature which isequal to the temperature of the sputtered target surface during steadysputtering.
 22. A method according to claim 13 in which annealing afterfinal target fabrication is performed gradientally by exposing thesputtered target surface to the same heating condition and exposing anopposite target surface to the same cooling condition as under targetsputtering during a sufficient time for steady annealing.
 23. A methodaccording to claim 22 in which gradient annealing of the target isperformed directly in a sputtering machine at sputtering conditionsbefore starting a production run.
 24. A method according to claims 4, 7or 8 in which the step of equal channel angular extrusion include afirst extrusion with 1 to 5 passes into different directionsintermediate annealing at a low temperature and for a time sufficient toproduce very fine precipitates of average diameter less than about 0.1μm, and a second extrusion with a sufficient number of passes to developa dynamically recrystallized structure.
 25. A method for controllingtexture of sputtering targets by a process according to claim 4 whereinthe step of equal channel angular extrusion is performed by changing thenumber of passes and billet orientation between successive passes in amanner to produce a desired final texture strength and orientation. 26.A method for controlling texture of sputtering targets by a processaccording to claim 5 wherein the step of equal channel angular extrusionis performed by changing the number of passes and billet orientationbetween successive passes in a manner to produce a desired final texturestrength and orientation.
 27. A method for controlling texture ofsputtering targets by a process according to claim 8 wherein the step ofequal channel angular extrusion is performed by changing the number ofpasses and billet orientation between successive passes in a manner toproduce a desired final texture strength and orientation.
 28. A methodaccording to claim 25 including a preliminary processing performedbefore extrusion to produce strong original texture of the sameorientation as of the desired final texture after equal channel angularextrusion.
 29. A method according to claim 25 including the additionalstep of recovery annealing performed between extrusion passes attemperatures below the temperature of static recrystallization.
 30. Amethod according to claim 25 including the additional step of recoveryannealing after equal channel angular extrusion at temperatures belowthe temperature of static recrystallization.
 31. A method according toclaim 25 including the additional step of recrystallization annealingperformed between extrusion passes at a temperature equal to thebeginning temperature of static recrystallization.
 32. A methodaccording to claim 25 including the additional step of annealingperformed after the step of equal channel angular extrusion at atemperature equal to the beginning temperature of staticrecrystallization.
 33. A method according to claim 25 including theadditional step of recrystallization annealing performed betweenextrusion passes at temperature above the temperature of full staticrecrystallization.
 34. A method according to claim 25 including theadditional step of recrystallization annealing performed after the stepof equal channel angular extrusion at temperatures above the temperatureof full static recrystallization.
 35. A method according to claims 4, 7or 8 wherein at least different types of thermal treatments areperformed between extrusion passes and after the final step of equalchannel angular extrusion.
 36. A method according to claim 4, 7 or 8further comprising a thermal treatment for control of grain size anddistribution of second phase particles.